Comprehension # 2
When two bodies collide normally they exert equal and opposite impulses on each other. Impulse `=` change in linear momentum. Coefficient of restitution between two bodies is given by :-
`e = |"Relative velocity of separation"|/|"Relative velocity of approach"| = 1`, for elastic collisionTwo bodies collide as shown in figure. During collision they exert impulse of magnitude J on each other.
For what value of J (in `N-s` ) the `2 kg` block will change its direction of velocity :-

Options

A. `J lt 12`
B. `J gt 12`
C. `J lt 10`
D. `J gt 10`

Answer

B

Explanation

By applying conservation of momentum
`2(6) + 1(4) = 1v_(2) + 2v_(1), 16 = v_(2) + 2v_(1)` ….(i)
By applying newton law of collision
`1 = (v_(2) - v_(1))/(2) rArr v_(2) - v_(1) = 2` ……(ii)
`rArr v_(2) = (20)/(3), v_(1) (14)/(3)`
To change the direction of a block impulse should be greater than `12 N-s`